What Dr. Ferber Said....
I also want to point out that emphasis on "as long as it works" is crucial. Ferber's switch to a more accepting attitude toward co-sleeping is such news in itself that I am worried that parents will overlook the fact that the true test of any sleep approach is how well the whole family is sleeping, Mom and Dad as well as the baby.
My own mistakes can serve as an example of how things can get off-track. My husband and I co-slept with our daughter for 9 months, then transitioned her to a crib. But I continued to get up and nurse her every time a heard a peep in the middle of the night. During the day, I was exhausted from the chronic sleep interruptions. Our daughter was still waking up several times a night when she was a year and a half old. Finally, we moved to a new house, and the first night my daughter slept in her own room, with the door closed, I slept uninterrupted and woke up feeling surprised and refreshed. I said to my husband, "She slept though the night!" and he said, "No, Amy, you slept through the night," because I hadn't heard her in her new room. And guess what, she was fine!
By jumping up every time I heard a peep, even into her toddler year, I was literally training her to expect me to come comfort-nurse her and reinforcing the cycle. I hadn't had the heart to "Ferberize" her early on, or try any of the sleep training strategies I had been recommended. I was almost defiantly proud that I was rushing to her side at every opportunity. But the costs were high: I was a sleep-deprived zombie, and my daugter wasn't learning to self-soothe. Wherever your children sleep, there are ways to ensure that everyone gets a good night's sleep after the newborn era has passed. As the parents, it's our responsibility to make sure this happens.
My own parent trainer, Donna Erickson, always said, "What's familiar is preferred," and to this day I think that's some of the wisest parenting advice I've received. I wish I'd taken more of her sleep advice to heart at the time, but it took a lot of my own experience to figure it all out! There are many sleep resources to consult for specific advice. My favorite reference is The Sleep Book for Tired Parents by Becky Huntley because she presents several philosophies in a balanced way, and helps you choose which one would work best for your family.